The individual characteristics of a firearm are the individual characteristics found on a cartridge case and bullet. These are the random marks produced incidentally during the manufacturing of a firearm by the tools and machinery. These are imparted inside a bore of a firearm during rifling.
What are individual characteristics?
Individual Characteristics are properties of physical evidence that can be attributed to a common source with a high degree of certainty. Examples of individual evidence include anything that contains nuclear DNA, toolmarks, and fingerprints. Examples: Types of Evidence.
What are the individual characteristics of a bullet?
Some of the class characteristics found on a fired bullet are (1) the caliber of the bullet (diameter), (2) the number of lands and grooves, (3) the twist of the rifling (left or right), and (4) the widths of the land and groove impressions.
What do you mean by class and individual characteristics?
Class characteristics are not unique to a particular object but place the particular bit of evidence into a group of objects. Individual characteristics narrow down the evidence to a single, individual source.\nThe type of handgun with which a victim is shot is a class characteristic.
Which of the following types of firearm characteristics are class characteristics?
Three class characteristics of a gun barrel are its caliber, the number of lands and grooves, and the direction and twist of the lands and grooves.
What is individual characteristic of cartridge cases?
Cartridge cases can often be associated with a particular weapon by breech face markings left on the primer cup. impressions, breech face markings, and extractor/ejector marks. ➢ Shot shells can be linked to a shotgun, analogous to cartridges from a handgun or rifle.
How does the afte define individual characteristics?
The AFTE Glossary defines Individual characteristics as: marks produced by the random imperfections or irregularities of tool surfaces. These random imperfections or irregularities are produced incidental to manufacture and/or caused by use, corrosion, or damage.
What is class characteristics of a firearm?
Class characteristics – Measurable features of a specimen that indicate a restricted group source. They result from design factors and are therefore determined prior to manufacture. In the context of this module, general rifling characteristics of the barrel of a firearm are the class characteristics of interest.
How individual characteristics are acquired?
An acquired characteristic is a non-heritable change in a function or structure of a living organism caused after birth by disease, injury, accident, deliberate modification, variation, repeated use, disuse, misuse, or other environmental influence. Acquired traits are synonymous with acquired characteristics.
What are examples of class characteristics?
Class characteristics can determine things like automotive paint types, blood types of people or a collection of new Phillips head screwdrivers, but cannot produce a specific match or individual identification. This type of evidence may be used to narrow down a list of possible sources.
What are class and individual characteristics of bullet?
Comparison of bullets involves "class" and "individual" characteristics. These characteristics are based upon "striae" left on the bullet as it passes through the barrel. Class refers to the type of caliber and rifling. Rifling pattern may turn to the right or left, with a given rate of twist.
What are the classification of firearms?
All firearms, whether military assault rifles or civilian pistols, are classified into three broad categories: fully automatic, semiautomatic and other. The groupings are based on how the weapon fires and loads bullets into its chamber for the next firing.
What is true about the use of class characteristics and firearm evidence?
What is TRUE about the use of class characteristics and firearm evidence? Investigators can determine the manufacturer and the gun type. There are two suspects in a shooting investigation. Bullets are recovered from the crime scene.
Are striations on a bullet class or individual evidence?
Striations, firing pin marks, and breechblock marks are all individual evidence. The direction of the twist, manufacturer, number of lands/grooves, caliber, etc. are all class evidence.
What is characteristics in forensic ballistics?
The class characteristics of bullets can be referred to as the caliber, direction of twist of the rifling, and the number of lands and grooves. These features are called class characteristics as multiple bullets can possess these characteristics that are not unique to an individual bullet.
What are examples of class characteristics?
Class characteristics can determine things like automotive paint types, blood types of people or a collection of new Phillips head screwdrivers, but cannot produce a specific match or individual identification. This type of evidence may be used to narrow down a list of possible sources.
Is rifling class or individual evidence?
Is this considered class or individual evidence? -Rifling is the spiral groove that are formed in the bore of a firearm. -It is used in some guns to stabilize the bullet as it shoots out. -It can be both class and individual, but mostly individual.
What is class characteristic?
Class characteristics are general and they are capable of tracing something back to a class or group. Eg. The caliber of a gun barrel or the number of lands and grooves in the barrel of a conventional rifled gun, etc. Pertaining to firearms, class characteristic are the intentional designed characteristics that are common to a particular group ...
What is individualizing characteristics?
Individualizing characteristics are unique to a firearm, hence causing the firearm to be unique as well, causing each firearm may be distinguished from other firearms. Individualizing characteristics of a firearm are typically seen at microscopic level.
What is the caliber of a bullet?
Caliber of the weapon. The caliber of the weapon is the diameter of the bore measured from land to land. The caliber is one of the most obvious class characteristics which is also imparted during the making of bullets (Tennessee State Court.gov, n.d.).
What is the shape of an ejector and an extractor?
The shape of ejector and extractor marks are also marks imparted onto the cartridge after firing (Hernandez, n.d.). The ejector and extractor can impart individualizing characteristics on the head of the shell casing, based on the theory that no two ejector and no two extractor is shaped the same way.
What are the marks inside a barrel that characterize that weapon?
The marks inside a barrel which characterize that weapon are not longitudinal, as produced by rifling cutters, but are rotational or spiral. These rotational marks are produced during the initial drilling and reaming of the weapon's bore and, as such, are totally random.
What are the marks inside a barrel?
The marks inside a barrel which characterize that weapon are not longitudinal, as produced by rifling cutters, but are rotational or spiral. These rotational marks are produced during the initial drilling and reaming of the weapon's bore and, as such, are totally random. They result from wear of the drilling tool, build-up of swarf on the cutting edge and hard inclusions in the metal's crystalline structure. Being rotational, they leave far more characteristic marks on a bullet passing over them than longitudinal striations.
How is a firearm identified?
A firearm is identified if there is sufficient agreement between the marks left at a crime scene and the marks made by the firearm in question. Before firearms can be analyzed, firearm evidence must be collected.
When a firearm is submitted for comparison, the examiner first determines that its class characteristics match those of the evidence?
When a firearm is submitted for comparison, the examiner first determines that its class characteristics match those of the evidence. If so, the examiner must discharge the weapon in a controlled environment to obtain casings and bullets from that weapon. The examiner then compares the individual characteristics of the laboratory-created cartridge cases and fired bullets to those of the evidence in question. Only then can the examiner determine if they are from the same source.
What is a firearm examiner?
Forensic scientists who analyze firearm evidence in the lab are typically called firearm examiners. The firearm examiner’ss job begins when firearm evidence arrives at the lab from the scene of the crime. The firearm identification process consists of several steps. First, the examiner may need to remove trace evidence from a bullet ...
What are class characteristics?
These are called class characteristics. Alternately, marks may be specific to that particular firearm (for example, corrosion of the rifling pattern contained in the barrel of the firearm.) These are called individual characteristics.
What is the process of analyzing bullets and cartridge cases left at a crime scene to determine if they came?
Firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. Marks on the bullets and cartridges may be common to every firearm of that type (for example, the caliber of the firearm). These are called class characteristics.
What are the characteristics of a bullet?
When a bullet is fired down a rifled barrel, the rifling imparts a number of markings to the bullet that are called "class characteristics." These markings may indicate the make and model of the gun from which the bullet has been fired. They result from the specifications of the rifling, as laid down by the individual manufacturer. These characteristics are:
What are the land markings on a bullet?
In contrast, for jacketed bullets, the land markings are the most pronounced.1 These individual characteristics are peculiar to the particular firearm that fired the bullet and not to any others. They are as individual as fingerprints. No two barrels, even those made consecutively by the same tools, will produce the same markings on a bullet.
Can two barrels produce the same markings?
No two barrels, even those made consecutively by the same tools, will produce the same markings on a bullet. Thus, while the class characteristics may be identical on bullets fired by two different weapons, the individual characteristics will be different.
